Kaoru Kanou, a corporate president who is under suspicion for arrest, holds a ballroom event. Among the invitees are Shinjūrō Yūki, a curious detective, his strange assistant, Inga, and Rie, the daughter of police detective Rinkako Kaishō. During the event, Kanou is mysteriously murdered by a knife in his back, with suspicions placed on a member of the SP police who was found shot dead in the hallway. However, thanks to Shinjūrō's detective work, along with the strange abilities of Inga, who transforms into an adult capable a forcing an answer to any one question she asks someone, they soon discover the culprit is Kanou's wife, who wanted him to die a hero.

Rie calls on Shinjūrō and Inga to accept a request from Mitsuko Sasa, whose adopted brother Kazamori caught on fire and died, allegedly related to a curse from her father, Komamori, who died in a similar manner seven years ago. As Izumi's group conducts their own investigations on the cause of Kazamori's death, Inga uses her powers to reveal that Kazamori is actually a supercomputer.